18 September 2007 Frequency response of the three Gaussian beam interferometric profilometer
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A novel technique based on the use of a three Gaussian beam interferometer to obtain roughness information about smooth optical surfaces is described. The technique is based on the heterodinization of three coherent optical beams. One of the beams is used as a probe beam after being focused and reflected from the surface under test. A second beam is generated to be reflected by a reference surface. The last beam is obtained from the first diffraction order of a Bragg cell and thus, it is shifted in its temporal frequency. The three beams are coherently added at the sensitive plane of a photodetector that integrates the overall intensity of the beams. It will be demonstrated analytically that the electrical signal at the output of the photodetector is a time varying signal whose amplitude is proportional to the surface's local vertical height. The frequency response of the proposed system is characterized experimentally by measuring the profile of three different blazed-gratings. Once the system is calibrated, we present measurements of the roughness of an optical flat.
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Lorenzo Juárez P., J. Mauricio Flores, Moisés Cywiak, Manuel Servín, "Frequency response of the three Gaussian beam interferometric profilometer", Proc. SPIE 6671, Optical Manufacturing and Testing VII, 66710E (18 September 2007); doi: 10.1117/12.734142; https://doi.org/10.1117/12.734142

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